1. Field of the Invention
The present invention relates to a multi-point distance measurement apparatus which determines a photographing distance by a plurality of distance information.
2. Related Background Art
In the past, it has been a common practice in a multi-point distance measurement apparatus to measure distances for a plurality of points and to focus a lens to a photographing distance to include an object within the depth of field.
However, in the prior art multi-point distance measurement apparatus, the lens is not always best focused to a principal object.
FIG. 5 shows a perspective view including two photographing scenes, a near scene and a far scene. In the near scene, two persons X.sub.1 and X.sub.2 stand beside each other at a position of a near photographing distance Rx from a camera 8, and one person X.sub.3 stands between the two persons X.sub.1 and X.sub.2 at a distance .DELTA.R behind them. In the far scene, persons Y.sub.1, Y.sub.2, and Y.sub.3 stand with the same positional relationship as persons X.sub.1 -X.sub.3, but with persons Y.sub.1 and Y.sub.2 at a far photographing distance Ry from the camera.
The near scene is typical for photography in a relatively small area, such as indoors, and the far scene is typical for photography in a relatively large area, such as outdoors.
FIG. 6 shows the relationship between depth of field and photographing distance. As shown in FIG. 6, as the photographing distance R.sub.m increases, the corresponding depth of field D.sub.m increases. Conversely, as the photographing distance decreases, the depth of field decreases. With respect to the scene in FIG. 5, it will thus be appreciated that whether the distance .DELTA.R is within the depth of field will depend on the applicable photographing distance. Consequently, when the photographer's intended principal object is the center person, whether or not the center person is within the depth of field will depend on whether the photographing is near distance photographing or far distance photographing. This presents a problem in that the photographer may or may not obtain a properly focused photograph of the intended principal object.
Further, in photographing a far scene in a flash mode, even if the photographing distance is set to a principal object, there is a potential problem in that the flash light may not reach the principal object so that a proper exposure is not obtained.